Determine the update path where the installer will look for new .airgap
packages. You can do this from the console settings of your instance
(https://<TFE HOSTNAME>:8800/console/settings) in the field Update Path.

Download the new .airgap package onto the instance and put it into the
Update Path location.

From the installer dashboard (https://<TFE HOSTNAME>:8800/dashboard) click the
"Check Now" button; the new version should be recognized.